Portable light tower



FIG. 1 is a top plan view of a portable light tower showing our new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a right elevation view thereof;

FIG. 4 is a left elevation view thereof;

FIG. 5 is a front elevation view thereof; and,

FIG. 6 is a rear elevation view thereof.

The broken line showing of elements are for illustrative purposes only and form no part of the claimed invention. 

The ornamental design for a portable light tower, as shown and described. 